· Professor Emeritus of Mathematics, Cornell University1985–
· Professor of Mathematics, University of California, Santa Cruz1979–1985
· Associate Professor of Mathematics, University of California, Santa Cruz1975–1979
· Assistant Professor of Mathematics, University of California, Santa Cruz1973–1975
· Lecturer, Massachusetts Institute of Technology1972–1973
· Doctor of Philosophy, University of California, Berkeley1970–
· Visiting Lecturer, IMPA (Instituto de Matemática Pura e Aplicada)1969–
· Senior Research Fellow, Institute for Advanced Study1969–1970
· Bachelor's degree, Harvard University1966–